I feel like part of the story line has been overlooked:

"wants to limit salary to the SocSec limit (to save PR taxes)"

Once you hit the limit, there are no more SS taxes, anyway. Limited to the limit or exceeding the limit doesn't change SS.

Medicare is 1.45% and then hits an additional 0.9%.

Fed UI tops out at $7,000.

This whole discussion is over 2.35%?